On its way: Flash flood watch issued for storms hitting us Wednesday

Courtesy: National Weather Service Brownsville

HARLINGEN — It could be a drought-breaker, but first we have to get through it.

The National Weather Service in Brownsville has issued a flash flood watch for the Rio Grande Valley from now until Thursday evening as a storm system begins to move from west to east across the Valley.

The front, accompanied by heavy rains and thunderstorms, should be hitting Valley cities sometime around mid-day Wednesday, and rainfall is expected to be significant.

“I think it’ll be widespread 2- to 4-inch amounts, but I think the thing we’re looking at here is there’s a potential for up to 4 inches or so localized,” Dave Houk, senior meteorologist with AccuWeather, said Tuesday. “But the big thing is, it’s going to be coming in a pretty quick period, a six- to eight-hour window, and that’s advancing from west to east across the Lower Rio Grande Valley during the day tomorrow.

“It could get into McAllen and those places by maybe late morning, Harlingen probably it waits until afternoon, and then a few hours later it will get down to Brownsville,” he added.

The weather system that is spawning these storms is a big one, and on Tuesday was centered over southern Colorado and northern New Mexico.

“And that’s been sending out little bits of energy eastward, along with very copious amounts of moisture, which has resulted in the heavy rains recently in the last couple of days of severe storms,” Houk said. “Most of that has been farther off to our north, but with the severe storms there was some flooding, and I saw some heavy rainfall amounts over in Beaumont, Texas, the Port Arthur area, Lake Charles, with nearly a foot of rain in some of those areas from one of these complexes.”

Houk stressed that the biggest threat to Valley residents is flash flooding, but he said there is a small chance of severe thunderstorms and even mini-tornadoes along the leading edge of the front as it arrives.

“Sometimes when you get these little lines going there are little spins on the front end of the line and you just get a quick little spin-up, isolated,” Houk said. “We call them ‘gustnado’ tornadoes.

“That’s kind of what the Storm Prediction Center would call a marginal or slight risk, which means we’re not expecting widespread activity, but it’s something we’re going to have to watch and see how things evolve.”

The anticipated downpours should help alleviate drought conditions in the Rio Grande Valley, which have been eased somewhat by rains in the past two weeks.

Every county in the Valley remains in some sort of drought phase as of last week, with coastal areas in moderate drought, western Cameron and western Willacy in severe drought, and most of Hidalgo County in severe drought with the northern third of the country in extreme drought.

“In a general, broad scope, it is beneficial,” Houk said.

The evolution of the coming storm is of particular interest. As the northern part of the storm continues to shed energy and lumbers away to the east, the southern part of the storm is expected to linger over the Valley and that could mean rain for several days.

“The southern piece gets left behind and it leaves a weak upper-level low down across Deep South Texas on Thursday, and it kind of sits there on Friday as high pressure builds in the eastern part of the country, it kind of retrogrades or builds westward,” Houk said. “So we think there’s still going to be a good push of moisture coming in from the southeast.

“It doesn’t look like anything kind of extreme … but there are going to be additional showers and thunderstorms, more of the pop-up, occasional variety, on Thursday, Friday, even into Saturday and Sunday.”

rkelley@valleystar.com